Re: Cannot bootstrap on NetBSD/cobalt

[Nozomu Ando <nand@mac.com>]

Nozomu Ando <nand@mac.com> writes:
> It seems that ld for elf32-tradlittlemips igonores "-z nocombreloc"
> option or there are some restrictions of binutils around MIPS elf.
>
> And unexelf.c cannot unexec correctly without "-z nocombreloc" with
> X11 dynamic-link libraries, because "undo relocations" at
> unexelf.c:1221 does not work.

The attached patch is for the two issue previously reported:

 * We cannot build GNU Emacs CVS HEAD on NetBSD on MIPS processor.
 * We cannot execute emacs with X11-related dinamic-link libraries.

For the latter issue, I wrote some code for unexelf.c so that
temacs can unexec without "-z nocombreloc" linker option
(if unexelf.c compiled with -DBROKEN_NOCOMBRELOC).

NAKAJI-san and I tested this patch on several platform:
 NetBSD-3.0 release on hpcmips (MIPS little endian)
 NetBSD-3.99.11 (binutils 2.15) on NetBSD/hpcmips
 NetBSD-3.99.7 (binutils 2.15) on NetBSD/newsmips (MIPS big endian)

Thanks,
---
Nozomu Ando

P.S.
We found also another problem on NetBSD-current with binutils 2.16.1.
Its start address of the data segment is changed.
We have a workaround for this, but I am not sure what is correct fix.

---
Index: src/unexelf.c
===================================================================
RCS file: /cvsroot/emacs/emacs/src/unexelf.c,v
retrieving revision 1.61
diff -u -c -r1.61 unexelf.c
*** src/unexelf.c	6 Feb 2006 15:23:21 -0000	1.61
--- src/unexelf.c	9 Mar 2006 15:18:19 -0000
***************
*** 433,438 ****
--- 433,441 ----
  #if __sgi
  #include <syms.h> /* for HDRR declaration */
  #endif /* __sgi */
+ #ifdef BROKEN_NOCOMBRELOC
+ #include <assert.h>
+ #endif
  
  #ifndef MAP_ANON
  #ifdef MAP_ANONYMOUS
***************
*** 687,692 ****
--- 690,698 ----
    int old_mdebug_index;
    struct stat stat_buf;
    int old_file_size;
+ #ifdef BROKEN_NOCOMBRELOC
+   int unreloc_sections[10], n_unreloc_sections;
+ #endif
  
    /* Open the old file, allocate a buffer of the right size, and read
       in the file contents.  */
***************
*** 1218,1223 ****
--- 1224,1230 ----
  
    /* This loop seeks out relocation sections for the data section, so
       that it can undo relocations performed by the runtime linker.  */
+ #ifndef BROKEN_NOCOMBRELOC
    for (n = new_file_h->e_shnum - 1; n; n--)
      {
        ElfW(Shdr) section = NEW_SECTION_H (n);
***************
*** 1272,1277 ****
--- 1279,1359 ----
  	  break;
  	}
      }
+ #else /* BROKEN_NOCOMBRELOC */
+   for (n = 1, n_unreloc_sections = 0; n < new_file_h->e_shnum; n++)
+     if (!strcmp (old_section_names + NEW_SECTION_H (n).sh_name, ".data")
+ 	|| !strcmp (old_section_names + NEW_SECTION_H (n).sh_name, ".sdata")
+ 	|| !strcmp (old_section_names + NEW_SECTION_H (n).sh_name, ".lit4")
+ 	|| !strcmp (old_section_names + NEW_SECTION_H (n).sh_name, ".lit8")
+ #ifdef IRIX6_5			/* see above */
+ 	|| !strcmp (old_section_names + NEW_SECTION_H (n).sh_name, ".got")
+ #endif
+ 	|| !strcmp (old_section_names + NEW_SECTION_H (n).sh_name, ".sdata1")
+ 	|| !strcmp (old_section_names + NEW_SECTION_H (n).sh_name, ".data1"))
+       {
+ 	assert (n_unreloc_sections
+ 		< (sizeof (unreloc_sections) / sizeof (unreloc_sections[0])));
+ 	unreloc_sections[n_unreloc_sections++] = n;
+ #ifdef DEBUG
+ 	fprintf (stderr, "section %d: %s\n", n,
+ 		 old_section_names + NEW_SECTION_H (n).sh_name);
+ #endif
+       }
+ 
+   for (n = new_file_h->e_shnum - 1; n; n--)
+     {
+       ElfW(Shdr) section = NEW_SECTION_H (n);
+       caddr_t reloc, end;
+       ElfW(Addr) addr, offset;
+       int target;
+ 
+       switch (section.sh_type)
+ 	{
+ 	default:
+ 	  break;
+ 	case SHT_REL:
+ 	case SHT_RELA:
+ 	  /* This code handles two different size structs, but there should
+ 	     be no harm in that provided that r_offset is always the first
+ 	     member.  */
+ 	  for (reloc = old_base + section.sh_offset,
+ 		 end = reloc + section.sh_size;
+ 	       reloc < end;
+ 	       reloc += section.sh_entsize)
+ 	    {
+ 	      addr = ((ElfW(Rel) *) reloc)->r_offset;
+ #ifdef __alpha__
+ 	      /* The Alpha ELF binutils currently have a bug that
+ 		 sometimes results in relocs that contain all
+ 		 zeroes.  Work around this for now...  */
+ 	      if (addr == 0)
+ 		continue;
+ #endif
+ 	      for (nn = 0; nn < n_unreloc_sections; nn++)
+ 		{
+ 		  target = unreloc_sections[nn];
+ 		  if (NEW_SECTION_H (target).sh_addr <= addr
+ 		      && addr < (NEW_SECTION_H (target).sh_addr +
+ 				 NEW_SECTION_H (target).sh_size))
+ 		    {
+ 		      offset = (NEW_SECTION_H (target).sh_addr -
+ 				NEW_SECTION_H (target).sh_offset);
+ 		      memcpy (new_base + addr - offset,
+ 			      old_base + addr - offset,
+ 			      sizeof (ElfW(Addr)));
+ #ifdef DEBUG
+ 		      fprintf (stderr, "unrelocate: [%08lx] <= %08lx\n",
+ 			       (long) addr,
+ 			       (long) *((long *) (new_base + addr - offset)));
+ #endif
+ 		      break;
+ 		    }
+ 		}
+ 	    }
+ 	  break;
+ 	}
+     }
+ #endif	/* BROKEN_NOCOMBRELOC */
  
    /* Write out new_file, and free the buffers.  */
  
Index: src/m/mips.h
===================================================================
RCS file: /cvsroot/emacs/emacs/src/m/mips.h,v
retrieving revision 1.27
diff -u -c -r1.27 mips.h
*** src/m/mips.h	6 Feb 2006 15:23:23 -0000	1.27
--- src/m/mips.h	9 Mar 2006 15:18:19 -0000
***************
*** 112,118 ****
  /* This machine requires completely different unexec code
     which lives in a separate file.  Specify the file name.  */
  
! #ifndef __linux__
  #undef UNEXEC
  #define UNEXEC unexmips.o
  #endif /* not __linux__ */
--- 112,118 ----
  /* This machine requires completely different unexec code
     which lives in a separate file.  Specify the file name.  */
  
! #if !defined(__linux__) && !defined(__NetBSD__)
  #undef UNEXEC
  #define UNEXEC unexmips.o
  #endif /* not __linux__ */
***************
*** 142,155 ****
  #if defined (__NetBSD__) || defined (__OpenBSD__)
  #else  /* bsd with elf */
  #define LINKER /bsd43/bin/ld
- #endif /* bsd with elf */
- #else /* not BSD_SYSTEM */
- 
- #if defined(__GNUC__) && defined(_ABIN32)
- #define LIBS_MACHINE
- #else
- #define LIBS_MACHINE -lmld
- #endif
  
  #define LD_SWITCH_MACHINE -D 800000 -g3
  #define START_FILES pre-crt0.o /usr/lib/crt1.o
--- 142,147 ----
***************
*** 159,164 ****
--- 151,165 ----
  #define C_SWITCH_MACHINE -I/usr/include/bsd
  #define C_DEBUG_SWITCH -O -g3
  
+ #endif /* bsd with elf */
+ #else /* not BSD_SYSTEM */
+ 
+ #if defined(__GNUC__) && defined(_ABIN32)
+ #define LIBS_MACHINE
+ #else
+ #define LIBS_MACHINE -lmld
+ #endif
+ 
  #endif /* not BSD_SYSTEM */
  #endif /* not NEWSOS5 && not __linux__ */
  \f
Index: src/m/pmax.h
===================================================================
RCS file: /cvsroot/emacs/emacs/src/m/pmax.h,v
retrieving revision 1.23
diff -u -c -r1.23 pmax.h
*** src/m/pmax.h	1 Sep 2003 15:45:58 -0000	1.23
--- src/m/pmax.h	9 Mar 2006 15:18:19 -0000
***************
*** 13,20 ****
--- 13,24 ----
  #ifndef __MIPSEB__
  #undef WORDS_BIG_ENDIAN
  #endif
+ #if defined (__NetBSD__)
+ #define BROKEN_NOCOMBRELOC
+ #else
  #undef LIB_STANDARD
  #undef START_FILES
+ #endif
  #undef COFF
  #undef TERMINFO
  #define MAIL_USE_FLOCK
***************
*** 24,41 ****
  #ifdef MACH
  #define START_FILES pre-crt0.o /usr/lib/crt0.o
  #else
  /* This line starts being needed with ultrix 4.0.  */
  /* You must delete it for version 3.1.  */
  #define START_FILES pre-crt0.o /usr/lib/cmplrs/cc/crt0.o
  #endif
! 
! #if defined (__NetBSD__) || defined (__OpenBSD__)
! #undef START_FILES
! #define START_FILES pre-crt0.o /usr/lib/crt0.o
! #undef RUN_TIME_REMAP
! #undef UNEXEC
! #define UNEXEC unexelf.o
! #endif /* NetBSD || OpenBSD */
  
  /* Supposedly the following will overcome a kernel bug.  */
  #undef LD_SWITCH_MACHINE
--- 28,39 ----
  #ifdef MACH
  #define START_FILES pre-crt0.o /usr/lib/crt0.o
  #else
+ #if !defined (__NetBSD__)
  /* This line starts being needed with ultrix 4.0.  */
  /* You must delete it for version 3.1.  */
  #define START_FILES pre-crt0.o /usr/lib/cmplrs/cc/crt0.o
  #endif
! #endif
  
  /* Supposedly the following will overcome a kernel bug.  */
  #undef LD_SWITCH_MACHINE